Tread link



Dec. 13, 1932. I A, ARMlNGTON 7 1,890,444

TREAD LINK Filed July 21, 1932 I 2 Sheets-Sheet l f INVENTOR 4 ARTHUR Him/Mara ATTORNEYS A. P. ARMINGTON TREAD LINK Filed July '21, 1952 2 Sheets-Sheet NJ m ATTO R N EYS Dec. 13, 1932.

Patented n... 13, 1932v nn'rnnn r. anmndron, or wInLou'ennY, onro TREAD LINK Application fl 1e d July 21, 1932. Serial No. 623,708.

, This invention relates to endless tread linkages of truss-forming or beam-forming type for employment as wheel substitutes 1n the running gear of slow-moving heavy-duty vehicles. 4 a A linka e capable ofso functioning is disclosed in atent No. 425,600 issued April 15, 1890,.to Edwards, and its manner of use 1s disclosed in Patent No. 1,458,962 issued June 19, 1923 to Athey; but the general type of link here contemplate is more similar to that shown in Patent No. 1,808,445 issued to me.

June 2, 1931.

In all of these linkages of the class de- '15 scribed one of the functions is that the mind-engaging stretch of the linkage have dam' characteristics that is, be inflexi le upwardly or inwardly between the wheels bearin on the ends of the stretch. From a consi eration of the form of linkshown in my observed that such flexing of the stretch is resisted by contact between adjacent links, first at the hinge means 5 by which they are 'connectedin the linkage,

and secondl at the cooperating truss members upstan 'ng from the ground-engaging shoe parts ofthe links. v p t It is highly desirable that the truss-forming stretch of linkage have an arch or bow outwardly or oppositely to the forces which it is to'resist as a beam, and this arch is customarily provided by making the pitch spacing' of the truss members slightly. less than that of the hinge means, as will be appreciated by one familiar with the art. Obviously wear at these contactin parts will reduce the arch of the stretch. ence to reduce such wear is hi hly important since by such reduction the attening or collapse of the arch is correspondingly reduced.

Patent No. 1,8 4,013, issued April 12, .1932, to me and others, and Patent No. 1,862,617 issued to me June 14, 1932, show two arrange- 4 ments whereby such wear is practically elim- "inated, and the latter of these patents and particularly its file history, exposes the theory 7, of the causes of such wear andthe consequent manner of its reduction. a The principal object of this invention is to said patent it will be pins 8 are securedin the openings 6 of the end accomplish a similar ultimate result, by simpler and more inexpensive means.

Wear at the hinge means is reducible only to a limited extent because of the motion at the hinge joints as the links have relative motion thereabout when passing between bends and stretches. Another object of the invention is to provide that as this unavoidable wear takes place at the hinge connections, the arch will nevertheless be maintained by a novel functional relation between the truss members. v 7

Further objects and advantages of the invention will be apparent from the following description takenin connection with the accompanying drawings, in which Figs. 1, 2 and 3 are plan view, end elevation and side elevation respectively of a link unit embodying the invention shown in ground-engaging position, as in a lower stretch of linkage, parts being broken away to show details of construction; and'Fig. 4 is a diagrammatic view'illustrative of the manner of functioning, proportions of the coperative' parts being exaggerated for better illustration.

With reference now to the drawings and particularly to Figs. 1-3 thereof, 1 is the shoe or pad part of the link having a generally flat ground-engaging surface 2. Above at its sides the shoe has rail surfaces 3; at one end the shoe has a pair of spaced lugs 4 and at its opposite'end three similar lugs 5 arranged in staggered relation with the lugs 4.

. The lugs 5 areprovided with aligned openings 6 to receive a hinge pin 7 of round bar 8 stock. The openings '6 may be cored and the relation between them and the hinge pin 7 is such that the pin may rotate. Retaining lugs 5 to position the hinge pin 7 endwise, yet allow its rotation. 9

The lugs 4 on the opposite end of the shoe likewise have'aligned openin s'which may be bushed as at 9 to receivetie hinge in 7 of th nextadjacent similar link in a lin age. 9

T us it will be obvious that an endless tread linkage may be made u of a plurality of links similar to t one s own.

Upstanding from the s part -1 of the link is a pair of truss members. One of these 1 truss members is in the formof a pair of ings 11, to allow a limited amountof rolling,

as will be described and the pin is posrtioned endwise therein by retaining pins 13 in a manner similar to that of mounting the hin pin 7. a

Vhile the diamet ical fit of the hinge pin 7 is desirably as t'ght as foundry and/0r inachinepractice wil allow without bindin provided rotation of the pin is permitte the diametrical fit of the truss pm 12 may bealooser one. ..These pins 7 and 12 must be permitted rotation in the functioning of the linkage, as will appear. Their mounting is what is own as of the floating type.

The truss pin 12 is a proximate y above one end of the'shoe 1 an the truss members 10 extend at their base parts toward the o o- I site end of the shoe as at 14. Upstan mg from the opposite end of the shoe is a cooperative truss men' iber 15' having its base art 16 extending between the members 10. he upper extremity of the member 15 is in the form of a hook 17 having a concave cylindrical surface 18 substantially corresponding with'the diameter of the truss p n 12. The surface'18 extends parallel with the truss pin, transversely of the link, substantially the distance of clearance between the faces 7 of thebrackets 10 adjacent the pin. The spac- .on the opposite ends of the shoe of the lin so that a stretch of the linkage will have a sli ht curvature. Y

Thus the link includes a pair of truss members, one in arched f ormvwith the projecting art of the truss pin 12that part extending tween the brackets lO-constituting the central or bridge ad 'acent link.

4 illustrates'astretch of linkage made i up o a number of such links wherein the hinge and truss. pins 7 and 12 are shown of exaggeratedly undersized diameter, as after a great deal of wear has occurred. It will be" seen that the hook member of each'link extends between the members 10 of the next adjacent link to engage the truss pin '12 supported by those members 10. Thus bend- I art of the arch, and the other a hook mem er adapted to cooperate with the-bridgepa'rt of the arch of itsnext mem rs downwardl and between the bra c ets supportin the latter.' It will also be observed that t e rails 3 of the links form a substantiall continuous pair of tracks, one on each side 0 the linkage.

ground-" Theloading of forces on such a engaging stretch of the linkage is illustrated by the. downwardly directed arrows B and C at the ends of the stretch and the u 'wardly directed arrow A intermediate the ends of the the o posite directionbg foldillllg of the hook omt eirtru in 4 stretch. In practice the forces B and G are of course set up by wheels running upon the the rails 3 and located at the force A the relative vertica dis lacement;

of adjacent. links is in o posite irections. The direction of motion 0 a vehicle sup ort- .ed"upon the linka e shown Fig. 4, won d be toward the left. bus in the stretch of the linkage the forceA may moving toward the left, as are the forces'B and'C. As the force A passes from one link onto the next there is motion between the be considered as links at both the hinge pin? and the truss pin 12 of the joint.

The broken line 19 is intended to indicate therelative disposition of the links in the stretch. In this line each relatively horizontal dot-dash line indicates the center line betweenhinge pin openings of one link,,while each relatively short generally vertical line indicates the displacement between two ad- 'acent link ends. This displacement retains its direction until the force A is passed at which time the direction is reversed and it is thence maintained throughout the stretch.

Specifically, it is the object of this invention-to reduce wear at the contactin truss forming parts during the motion t erebetween when this displacement change occurs.

, The operation is quite simple. As the force A progresses relative to the stretch of -linkage, and adjacent links have relative motion at their joint, the corresponding hin e pin 7 and the truss pin 12 simply act as refiers between the parts which bear against them so that there is no'sliding friction between those parts.

The oppositely directed faces of the truss members between which. the truss ins 12 bear, for transmitting the .trussorming stresses between links, will be noted as concavel curved. Consequently when adjacent inks have relativel translatory motion generally vertically as when passing the force A, Fig. 4, such pair of links will-becau'sed relative angular motion about theihinge connection which joins them, in adirection to oppose the loadin of the forces A, B and C.

11 other words, the trussforming parts of the adjacent pair' of links on the stretch.

' apprec ated'that-a good fit may be had between the pins and their bearing parts so that thisqmotion will be actually very slight. Nevertheless, however close the fit, provided the fit allows rolling of the pins-that is,

provided the. fit is not tight-there will be some motion between as the force A is passed. This motion, however slight, will be accompanied by the described roller action of. the hinge vand truss pins, whereby sliding bearing is substantially eliminated.

When a plurality of links as described are assembled in an endless linka e to form a track, and the track is mounte upon. a pair between bends an.

of wheels, with bends about the wheels and stretches therebetween,all as is customary in the art and the entire assembly is put e into service, therewill be relative an motion. This motion will cause sliding eararranged to be efiective between said faces rovide antifriction characteristics for.

to the1r relative translatory motion permitted by looseness at said hinge connection, at least one of said faces being concavely curved whereby upon relative translatory motion of said links permitted by looseness at said hinge connection when said links are operating in a truss-forming stretch of linkage, sald links .will be caused relative angular motion about said connection in a direction to op pose the loading on said stretch.

In testimony whereof Ihereby afiix my slgnature.

- ARTHUR P. ARMINGTON.

ing upon the bin e pins as' the links pass i stretches of the linka e, so that the fit at the hinge pins will gra ually become looser. Obv1ousl the looser the t the hinge connections t c more vertical motion will'take place between links as the force A, Fig. 4, ispassed. The greater such relative vertical motion, however, and themore'consequent vertical motion between cooperative truss members upon the common truss pin therebetween, the more will adjacent lmks be caused relative angular motion about their hinge connection in a direction to increase the arching relation therebetween.

What I claim is: 1. An endless tread linkage composed of articulate links, each adjacent pair of links having rail-carrying ground-engaging shoe arts with hinge means connect? their ad- ;acent ends, truss members upwa y extendmg. from said shoe parts and having oppositely directed bearing faces for transmittm truss-forming stresses between said links, an roller means arran to be effective between said faces to PIOVldQ wear-preventing characteristics for their relative translato tion, permitted by lost motion at said nge connection due to wear when said links are operating in a truss-forming stretch of hnkage. v

" 2. A tread linkage com of articulate links, each adjacent pair 0 links having railcarrying groundengagin shoeparts wlth means connectm truss members upwa shoe parts and having ORPOSItB y bearing faces for transmitting truss-formingbetween said links, and roller means y extendin from sin is air adjacent ends 

